🔍 Key Concepts

• Sagnac effect and how light behaves in rotating frames • Role of multiple fiber coils in measuring rotation about three axes • How a level sensor or accelerometers help isolate the horizontal component that points to true north

💭 Think About

• Ask yourself: Does a gyrocompass need to measure rotation about one axis or all three axes to resolve true north on a moving vessel? • Consider which combination of coils and sensors would allow the instrument to stay correctly referenced to the Earth’s horizon and filter out pitch/roll of the ship. • Think about whether a gyrocompass fundamentally measures linear acceleration or angular rotation of the Earth using light paths.

✅ Before You Answer

• Verify how many fiber-optic coils are typically used to sense rotation in 3D space (x, y, z axes). • Check whether a level sensor (to keep track of tilt) or multiple accelerometers is more consistent with stabilizing and referencing the unit to the Earth’s horizontal plane. • Confirm whether the focus of the device is measuring angular rotation (gyroscopic effect) rather than linear acceleration as its primary function.